New Mill losing steps

[JAZZCNC]

Eddy's correct and to do the maths we need the screw pitch. . .BUT . . . There is another way to do this if you don't know. (thou in your case it's not hard to find out)
In Mach on the settings Tab there is an option to "Set steps per Unit" it's just above the reset button.

To do this you will need to accurately measure how far the machine moves. (Tape measure isn't accurate enough)
when you click the button it will ask which Axis to calibrate then after this it will ask how far to move. Enter an amount, soon as you click enter the machine will move in a positive direction. Mach will then ask how far it moved, so measure distance and enter into box then it will calculate the STEPS PER for you.

Do this for each axis and you'll be set. The longer the distance you can measure and the more accurate the better.